Back with a follow up post a day late. Didn't test all that much so I apologise if any of these are due to me using an old save or something. If you can't immediately reproduce any of these then forget about it and tell me to try again. Hopefully my eyes will be less sore tomorrow so I can resume actually playing and do a bit more testing in the process.
1) Unfortunately the black box issue is still present for me on the 29-3 version. I tried deleting the settings.json file and then starting a new game, the box still appeared blocking over half the screen upon being regurgitated. Here is the relevant section of the papyrus log, not sure if it'll help at all.
[05/01/2021 - 11:15:47PM] DevourmentBellyScaling.OnPlayerStruggle(TRUE, 0.200000, 1.000000)
[05/01/2021 - 11:15:47PM] DevourmentBellyScaling.OnPlayerStruggle(TRUE, 0.200000, 1.000000)
[05/01/2021 - 11:15:47PM] DevourmentBellyScaling.OnPlayerStruggle(TRUE, 0.200000, 0.500000)
[05/01/2021 - 11:15:47PM] DevourmentBellyScaling.OnPlayerStruggle(TRUE, 0.200000, 1.000000)
[05/01/2021 - 11:15:48PM] DevourmentBellyScaling.OnPlayerStruggle(TRUE, 0.200000, 1.000000)
[05/01/2021 - 11:15:48PM] DevourmentBellyScaling.OnPlayerStruggle(TRUE, 0.200000, 1.000000)
[05/01/2021 - 11:15:48PM] devourmentmanager.VOMIT_LOCK(LOCKED WITH SLOT 0)
[05/01/2021 - 11:15:48PM] devourmentmanager.VOMIT_LOCK(PREY ALREADY LOCKED: TRIES=1)
[05/01/2021 - 11:15:49PM] devourmentmanager.VOMIT_LOCK(PREY ALREADY LOCKED: TRIES=2)
[05/01/2021 - 11:15:49PM] DevourmentLocationTracker.OnEffectFinish(Prisoner 0x14)
[05/01/2021 - 11:15:49PM] devourmentmanager.VOMIT_LOCK(PREY ALREADY LOCKED: TRIES=3)
[05/01/2021 - 11:15:49PM] Error: Cannot call RemoveSpell() on a None object, aborting function call
stack:
[alias PlayerAlias on quest DevourmentManager (FE00196A)].devourmentplayeralias.StopPlayerStruggle() - "DevourmentPlayerAlias.psc" Line ?
[alias PlayerAlias on quest DevourmentManager (FE00196A)].devourmentplayeralias.onEndState() - "DevourmentPlayerAlias.psc" Line ?
[alias PlayerAlias on quest DevourmentManager (FE00196A)].devourmentplayeralias.GotoState() - "Alias.psc" Line ?
[alias PlayerAlias on quest DevourmentManager (FE00196A)].devourmentplayeralias.gotoDefault() - "DevourmentPlayerAlias.psc" Line ?
[DevourmentManager (FE00196A)].devourmentmanager.ReappearPreyAt() - "DevourmentManager.psc" Line ?
[ (FF0042C1)].DevourmentVomitActivator.vomitLive() - "DevourmentVomitActivator.psc" Line ?
[DevourmentManager (FE00196A)].devourmentmanager.getNextVomit() - "DevourmentManager.psc" Line ?
[ (FF0042C1)].DevourmentVomitActivator.OnInit() - "DevourmentVomitActivator.psc" Line ?
[05/01/2021 - 11:15:49PM] WARNING: Assigning None to a non-object variable named "::temp20"
stack:
[alias PlayerAlias on quest DevourmentManager (FE00196A)].devourmentplayeralias.StopPlayerStruggle() - "DevourmentPlayerAlias.psc" Line ?
[alias PlayerAlias on quest DevourmentManager (FE00196A)].devourmentplayeralias.onEndState() - "DevourmentPlayerAlias.psc" Line ?
[alias PlayerAlias on quest DevourmentManager (FE00196A)].devourmentplayeralias.GotoState() - "Alias.psc" Line ?
[alias PlayerAlias on quest DevourmentManager (FE00196A)].devourmentplayeralias.gotoDefault() - "DevourmentPlayerAlias.psc" Line ?
[DevourmentManager (FE00196A)].devourmentmanager.ReappearPreyAt() - "DevourmentManager.psc" Line ?
[ (FF0042C1)].DevourmentVomitActivator.vomitLive() - "DevourmentVomitActivator.psc" Line ?
[DevourmentManager (FE00196A)].devourmentmanager.getNextVomit() - "DevourmentManager.psc" Line ?
[ (FF0042C1)].DevourmentVomitActivator.OnInit() - "DevourmentVomitActivator.psc" Line ?
2) Is opening the menus supposed to be blocked while swallowed? I'm able to access my inventory and magic menu as normal. If it is intentional that you can still open the menus then there's a few issues with it. First of all I am able to consume potions, including healing potions, however they appear to not affect the digestion health bar. Secondly I can change my equipment and equipped spells, doing so causes the equip noise to repeat rapidly and seems to break or slow down everything. In my testing the struggle mechanic either failed to work or became delayed and unresponsive, I also regained character control to an extent causing interact prompts to appear on the screen again, e.g. I could interact with a snow pile from iNeed, presumably near wherever my character was moved to when swallowed.
3) The player's prey health, digestion progress and struggle bars still fail to show on previous saves. I heard you figured this one out and it will be fixed in the next version though.
4) The flush vomit queue option added in the debugging section of the MCM displays as $DVT_FlushVomitQueue.
5) The skull duplication issue is fixed, nice work. However when I swallow skulls and begin to reform them my character's butt will inflate as if the NPC is ready to be defecated. It'll gradually deflate again as the NPC is reformed and the belly inflates. I don't recall this happening on previous versions and didn't see it in the patch notes so I'm assuming it's a bug and not a feature.
6) When reforming multiple NPCs at the same time they hang at 100% until the rest finish. Only when all of the currently reforming NPCs hit 100% will it switch them all to non-lethal at the same time and allow regurgitation.
7) My character slides slightly every time I use the burp power with something swallowed. Doesn't matter whether it's an actor or an object. Not sure if I only just noticed this or if it's a new bug. I tried moving around and facing different directions and still got pushed ever so slightly in the same direction every time.
8) I tried using the "Reset Devourment" debugging option and it didn't seem to do anything. I still had all of my stats, no completion message popped up, nothing showed up in the console etc. Might be due to upgrading from previous versions on that save or me breaking something though.
Thanks for your hard work as always.